A Becquerel (Bq) is one disintegration per second (as measured by a detector). The natural detected levels are normally at 0.5 Bq (mostly caused by potassium.
Notice that detected and actual disintegrations per second are not the same: these detected natural 0.5 Bq correspond to some 4,000 actual disintegrations inside our body every second, so 20,000 detected Bq must mean some 160 million disintegrations, four orders of magnitude above the natural base.
This man had 20,000 Bq measured on his body, while his wife had 10,000 Bq.
Iori Mochizuki says that the biggest health risk for Japanese is the accumulation of radiation because of contaminated food. This such sad situation could have been controlled by the state if they would not have gone nuclear fanatic spreading the radioactive materials instead of containing them.
For that reason I consider the Governments of Japan and their political and socio-economical allies criminals against humankind.
Source and some more medical info on how radiation causes heart collapse: Fukushima Diary.